Phase-sequence relay



' Sprl3;j19z9'. A T AL" j 11,726,928

4PHASE SEQUENCE RELAY 1 Original Fied Jan. 8-I 1924 5 Sheets-Sheet lwlTNI-:Ssl-:s: vENToRs D l Har/Ve 5@ ev an@ 55:73@ am Char/SY ge@ friscue ATTORNEY Sept.' 3, 192 9.

Original Filed.Jan.

5 Sheets-Sheet 3 K x W f l V I l 1 Il I .l

l l' l l l i I L/ "f L il 'IQ f 1 l l 1 l l l H\\ l l x 1 ii i; :1 l Il11 f Y wl 23 l? l1 1| i l l 1' ll AI3 ag W-TNESSES:

INVENTORS Har v@ S/efper and Sept. 3, 1929,

H. P. sLEEPx-:R ET Al. Y 1,726,928

PHASE SEQUENCE RELAY Y Original Filed Jan. 8v, 1924v 5 Sheets-Sheet 4Bm; AIE

` WITNESSES: INVENTORS a Ham/eff? Shaper and CCR W f Char/e5 L./L/eScL/e ATTORNEY H. P. sLEEPER n'ET Al. 1,726,928'

PHASE SEQUENCE RELAY original Filed Jan. 8, 1924 Y 5 sheets-Sheet' 5ATTORNEY Patented Sept. 3, 1929.`

UNITED STATES PATENT oirplclgp HARVEY P. SLEEPER, OF NEWARK, NEW JERSEY,ANDl CHARLES LE G. FORTESCUE,

OF PITTSBURGH, PENNSYLVANIA, ASSIGNORS TO WESTINGHOUSE ELECTRIC ANDMANUFACTURING COMPANY, A CORPORATLON OF PENNSYLVANIA.

' PHASE- SEQUENQE RELAY.

Application sied January s; 1924, seriar Na'esspco. Renewenay 9, 12529.

Our invention relates to electrical protective devices and moreparticularly-to phases'equence relays.

One object of our invention i's to provide a phase-sequence relay thatshall be adapted to protect a polyphase circuit under 'conditions ofoverload-or short-circuit, phase unbalance, open-phase and phasereversal.

` Another object of our invention is .tol provide a. time element relayt-hat shall operate only in response to the. positive or negativephase-sequence component of the currents in a polyphase circui Stillanother object'of ou'r invention is to providea unitary relay thatshallfc'mbine the functions formerly secured only by'the employment of aplurality ofseparate relay structures. .Y

A further object of our invention is topro- Vide a relay of improvedconstruction that distinguishes between positive and negativephase-sequence components of current.`

Heretofore, 1t has been necessary to provlde relays in each phase of apolyphase circuit in order to protect the circuit against conditions ofoverload and short-circuit, phase-reversal, open phase o rphase'unbalance. Such instruments are expensive andthe number 'of suchinstruments required to .adequately protect any polyphase circuit fromthe many interruptions to service towhich such lines lare subjected, isexcessive. With our improved relay, the above. enumerated protective'features are obtained. by the use of a single instrument that operatesin response to an abnormal positive phase-'sequence component orlnegative phase-sequence component of current caused by a fault,irrespectiveof the phase or phases involved in the fault.

Inour relay, an impedance network is provided of such character that twobranches thereof are traversed by currents proportional to the positiveandl the negative phasesequence components of the currents in thephaseconductors' of an associated polyphase circuit under allconditions. A relay is connected in each of the respective branches ofthe network and is energized in accordance with the magnitude of thecorresponding symmetrical component, the.pos1tive phasesequence.component being a measure of the overload and thenegativephase-sequence component being a measure of the-unbalance Fig. 4is a-diagrammatic view of apparatus' and circuits embodying ourinvention.

. Fig. 5 is a diagrammatic view of a different arrangement of circuitsand apparatus.

Fig. 6 is a vector dia ram of the currents traversing our relay undernormal condition of phase balance.

Figs. 7 and 8 are-.vector diagrams of the currents traversing our relayunder conditions of phase reversal.

Figs. 9 to 11, inclusive, are vector diagrams of the currents traversingour relay under conditions of open phase.

Fig. 12 is a vector diagram of a threephase unbalance; and

' Fig'. 13 Ais a diagrammatic view of circuits and apparatus showing ourrelay used in combination with a grounded 'polyphase circuit.Referring-to Fig. 4, `our invention comprises, in general, a unitaryrelay structure 10 'that embodies `a resistor 11, reactors 12 and 13,andthe winding 14 of a relay.` These parts are connected in an impedancenetwork the reactor 12 and the windings of the relay 14 are equal.- Thereactor l2 may take the form of a winding 15 of a second relay, as shownin Fig. 5. The relays comprising the windings 14 and 15 may be connectedto a .suitable circuit interrupter or other electrical devices (notshown) for controlling the. polyphase circuit 18. Y

Referring to Figs. 1 and 2, the'relay com- .opposite upper corners ofthe base member 21, Between `them are'disposed a plurality of spoolshaving coils thereon constituting the resistor 11. yOn' thejlower halfof the base 21 is mounted a relay 25that comprises the Winding 14,a'.pivoted armature member .19 controlled thereby a stationary Contactmember 27 and a movable contact member 28 secured to' thearmature member19 and controlled b y the current traversing the winding 14. Dampingmagnets 2O arepro vided for retarding the movement of the armaturemember 19. The relay 25 'is of the overload induction type'having aninverse or definite time-element characteristic Vand since its functions'and details of operation are well known Ain the art, a descriptionthereof is believed toF` be unnecessary, except in so far as 'it isnecessary to complete the combination with the remaining component partsof my invention.

Referring to Figs. 4 and 6, under conditions of current balance in thecircuit 18, the currents traversing the several. phases A, B and C arenormally 120 degrees apart.

y The current from the -current transformer 16 that is connected inphase A is delivered to the impedance network between the arms 1l, 12and 13,`14,"while the `current from the current transformer 17, that `isconnected in -phase B, is delivered-to the impedance.

network between the arms 11, 14 and l2,

No current transformer is placed in the phase C for the reason that anydisturbance between phase C and either of the otherphases A or B will berecorded by an unbalance in the affected phases.

Underbalanced conditions, the current from the phase A traverses theparallel circuits comprising resistor 11 and winding 14,

j and reactor 12 and reactor 13. By reason of the relation of theresistor 11 to the resistance and reactance of the reactor 13, which isof the same absoute impedance, 'a current proportional to 'the positivephase-sequence component traverses the reactor'12 and acurrent'proportional to the negative phase-sequence component traversesthe relay wind- .ing 14. As is shown in Fig. 5, the fact that bothpositive and negative phase-sequence components traverse the networkvmay be taken advantage of by having the reactor 12 comprise the Winding15 of a second relay 26 responsive to the magnitude of the positivephase-sequence component, thereby providing overload and short-circuitprotection to the 'circuit 18.

Referring to Fig. 6, the currents A14 and B11 derived from phases A andB are norinally egual in amount and opposite in direction under balancedconditions, thereby vequalizing one anotherwith the result that nocurrent traverses the winding 14 of thev relay 25. Under' unbalancedconditions, a currentproportional to the negative phasesequencecomponenttrarerses said winding.

Asshown in Fig. 44, the current AnlagsV the current A11 by an angle of60 un'der balanced conditions hecauseof the greater reactance of thebranch 13 with respect to the branch. 11 of the network. The sum of thecurrents A12 and A11 is equal to the current in-the phase conductor A(see Fig. 6). In a similar manner, the current B12 lead the curr'ent B11by an angle of 60 under balanced conditions and the. sum of the currentsB12 and B14 is equa-l to the current 1n the phase,

is proportional under all conditions to the positivephase-sequencecomponent of the c urrents inthe distribution circuit and lthe sum ofthe 4currents A1,1 and B11, which traverses the branch 14 of thenetwork, is proportional to negative phase-sequence component. Under`balanced current conditions, which are shown in Fig. (3, the positivecomponent is maximum and the negative component is zero. Various otherconditions are `illustrated-in Figs. 7 to 12.

Referring to Fig. 7, upon the occurrence of a reversal betweenthefphases A and B,'the currents A12 and B12 are substantially'equal andopposite in direct-ion with thc result that substantially no currenttraverses the reactor 12 whilethe sum of the currents ,A11 and B14traversingthe winding 14 becomes of an ap.- preciable value withtheresult that the relay 25 is operated to control any desired mechanismconnected with the circuit 18, such as a circuit interrupter (notshown).

Similarly,.upon the reversal of phases B 'and C, the positivephase-sequence components ate the negative phase-sequence relay 25. Bycomparing Figs. 7 and 8, it .will be seen that the vector. diagrams areidentical except for the fact that the 'relatively angular displacementof similar components is different.

Referring to Fig. 9, there is shown a vector diagram of the currenttraversing the relay when phase C is open. In this case, the currents Aland B are-equal and oppositein di- 'either event. a negativephase-sequence current of an appreciable value traverses the ofcurentbecome effective to operwinding 14 of the relay 25 that isoperated.

Referring to Fig. 12,` a condition of three-- phase unbalance isshownwherein the currents A, B and C are displaced at other lthan- 120degrees. It will thus be seen that the vresulting nevativephase-sequence current 14 y has-an appreciable value and, therefore,op-' crates the relay 25.

Referring to Fig, 13, if the phase-sequence relay is to operate on afdistributing system having a neutral point grounded as at 31 and 32, itmay be undesirable to have it influenced by the zero phase-sequencecomponent of eurrent. in which case the disposition of the currenttransformers may be such as to eliminate the zero phase-sequencecomponent from the circuits of the relay. This result is securedbyproviding the current transformers'33 and 34, correspondingto the relays16 and 17, of

y Fig. 4, respectively, with two primary windeliminated therein. .Therelay is therebyren-- dered independent of current in the groundedcircuit-which' is the zero phase-sequence c urrent and provlsion 1s madefor protection against groundsby interposing a suitable 4instrument 39in the` grounding lead for op-- erating o n a predetermined value'ofgroundcurrent. L

It will thus be seen that we have provided a relay that is responsiveto'the value of the positive and negative phase-sequencel cur.` rents'inthe polyphase circuit.' We have also provided a singleunitary relay thatis responsive to any Afault that 4produces y an un'- balanced currentcondition, irrespective f.v the phase or phases affected thereby. Sincethe positive phase-sequence current is ameasure of the overload orshort-circuit ,conditions in the circuit'and sincethe negativephasesequence current isa measure of phase unbalance, phase reversal andopen-phase condi-l tions, two relays embodying'r our invention willafford all the desired protection for a Apolyphase electrical circuit.,One ofv the' ad;

vantages of our invention, as will' appear, is that a great saving 1nthe use of' 1current transformers, as well asof relays, 1s effected'.while still obtaining complete circuit protection.

Furthermore, thenegative phase-sequence relay with a time-element orretarded opera.-

tion has an important application inlarge distribution systems in whicht-he unbalance of the system currents upon the occurrence of a fault isgreater in certain portions of thesystemA than in other portions. Sincethedegree of-energization of the relay depends upon the magnitude of thenegative phase-sequence quantity o r, in other'words, upon the amount ofunbalance of the system,`tlie time of operation of the relay' varies inaccordance with its relatiOntOtlie'auIt. In this manner,selectivedisconnection ofthe faulty portion ofthe distribution systemmay be obtained.

We do not wish to be restricted to the specific circuit connections orarrangement of .parts herein set forth, as 'various modificationsthereof may be effected without departing from the spirit and scopeof-our invention. Ve dcsire,lther'vefore, that only such limitationsshall be imposed as are indicated vin the appended claims.

lVe claim as our invention:

1.' Anelectrical protective device comprising an impedance networkconsisting of a winding of a relay, a resistor and a pair of reactors,'one of said reactors having the same resistance and reactance as thewinding of the relay. l

2. An electrical protective device comprisin'g al quadrilateralimpedance network consisting of a Windingof a relay, aresistor and i apair of reactors, one of said`reactors having the s'ame resistance andreactance as the winding ofthe relay, being disposed on an opposite sideof the impedance network relative to the winding of the relay. 3. Anelectrical protective device comprising a quadrilateral impedancenetwork consisting of aavinding of a relay, a resistor, and

a. pair of reactors, one of said reactors ha ving the 'same resistancevand reactance as the winding of the relay, .and being disposed on anopposite side of the impedance network relative to the v vindingof therelay, said reactor constituting an element of a second relay.

4. The combination withl a'polyphase electrical eircnit, a relay and aplurality of transformers connected to said circuit, of an elec- .tricalprotective device comprising a quadrilateral impedance networkenerg-ized from `said transformers comprising a winding of Qthe relay,a-'reslstor and a pair 'of reactors, the,

winding of said relayand a reactor of equal resistance and reactanceconstituting opposite sides of the impedance nctworln v5.- Thecombination with a polyphase electrical circuit, arelay and 'a'plurality of transformersconnected to-said circuit, of an electricalprotective device comprising an impedance. network in the form of abridge having opposite points connected to each of therespectivetransformers consisting of a winding of the relay, a resistorand a pair of reactors, the winding of said relay and a reactor of equalresistance and reactance constituting opposite arms of the impedancenetwork, whereby said relayis caused'to operate only in -response'toone' phase-sequence component of the current in the polyphase circuit.

trical circuit,

the winding of said relay `ance networkengrgized winding ofeach of lnetwork causes the 6. The combination with a polyphase elecva relayandtwo transformers connected in separate phases of said circuit, of anelectrical protective device .comprising an impedance bridge networkenergized from vsaid transformers consisting of a winding of pai'r ofreactors,l

the relay, a resistor and a and a reactor of equal resistance andreactance constituting opposite arms of"'tlie'impedance network wherebythe relay is caused to-operate in ac-` cordance with thenegative-pliasc-sequence component of the current traversing the circuitwhich is a measure of the conditions of open phase, phase imbalance,unsymmet'rical short circuit, and phase reversal in said circuit. c 'i7. The combination with a polyphase electrical circuit, a relay and a.plurality of transormers connected to said circuit, of an electricalprotective device comprising a quadrilateral impedance network.energized from said transformers consisting of a winding of the relay, aresistor and a pair of reactors, the

winding of said relay and a reactor of equal resistance andreactanceconstituting opposite arms of the impedance networkand the resistor andother reactor constituting the other arms'of the network and having suchrelative characteristics that the relay is caused to operate underconditions of phase f unbalance in said circuit.

8. The combination with a polyphase electrical circuit, a relay and twotransformers connected to'separate phases of saidcircuit, of anelectrical protect-ive device comprising an impedance bridge network,having opposite points connected to each of the respective transformersconsisting of a winding of the relay, a resistor and a pair of windingof saidrela'y and a reactor of equal resistance and react-anceconstituting opposite arms of the impedance network `and the resistorand the other reactor constituting the other arms of the network andhaving. suchrelative characteristics that the relay is caused to operateunder open-phase conditions insaid circuit. .I i

9. The combination with a polyphase electrical circuit, a relay and twotransformers connected to separate phases of saidcircuit, 0f anelectrical protective device comprising an impedance bridge networkhaving opposite points connected to each of the' respectivetransformers, a winding of the relay forming one-of the branches of saidnetwork.

10.- The combination with a polyphase electrical circuit, a plurality ofconnected transformers, and a pair of-relays, `of an impedfro'm saidtransformers consisting of a resistor. a reactor .and a said relays,whereby said operation of one of said relays upon the occurrence ofnegative-phasereactors, the v sequence currents in said circuit and saidnetwork causes the operation of the other relay under conditions ofexcessive positive phasesequence currents in said circuit. 11. Thecombination with a polyphase electrical circuit, a relay and a pluralityof transformers connected to said circuit, of an electrical protectivedevice comprising an impedance formers consisting of. a winding of therelay, a resistor anda pair of reactors, the winding of said relay and areactor of equal resistance currents.

13. An electrical ing an impedance bridge network for segregatingnegative phase-sequence currents from' positive phase-sequence currentsand means for selectively responding to currents of apredetermined'phasesequence.

14. An electrical device comprising a quadrilateral bridge networkresponsive to both positive and negative sequence currents inde-,

pendent of-sequence voltages for segregating and reactance constituting'opposite arms of protective device comprisbranch a member operative inresponse to positive phase-sequence' network energized from saidtranssov protective device compristhe negative sequence currents fromthe positive sequence currents, and means selectively responsive tocurrents ,of predetermined phase sequence for trical device.

15. The combination with afpolyphase electrical circuit, a pair ofrelays, means, comprising a plurality of current transformers, for

eliminating zero sequence currents from the pair of relays, of -anotherrelay ,responsive to zero sequence currents alone, and an impedancebridge network energized from the' transformers consisting'of aresistor, a reactor and a lwinding of each'of said pair of relays,

' whereby said vbridge networkcauses the operation of one of said pairof relays upon the occurrence o f'negative sequence c urrents in saidcircuit Vand said bri'dge networkcauses the'operation ofthe other ofsaid pair of relays in response to excess positive sequence currents insaid circuit.-

16. The' combination with a polyphase elecinluencing another elecizotrlcal circuit,'of means for separating out or segregating both thepositive and the negative sequence currents from the zero sequencecurrents in the circuit, means responsive to the last-named means and'comprising a quadrilateral bridge network for segregating the negativesequence currents from the positive sequence currents, and meansselectively and l separately responsive to predeterminedsephase-sequence quantities of said circuit, and quence currents forinuenoingvanother eleomeans for eliminating the zero phasesetrioaldevice. quenee quantities from said control means. 10

17. In combination With an electrical cir- In testimony whereof, .Wehave hereunto 5 cuit having acircuitinterrupter therein, of subscribedour names.

means for controlling the operation of'said HARVEY P. SLEEPER. A vinterrupter including means responsive tov CHARLES LE G7 FORTESCUE.

